The total is the highest quarterly number of expatriates since a law requiring the publication of their names was enacted in the 1990s, according to Andrew Mitchel, a lawyer in Centerbrook, Conn., who tallies the lists of names. The previous quarterly record was 1,130 for the second quarter of 2013, he says.

The new figure puts 2015 on pace to exceed the total of 3,415 renunciations in 2014, which was itself a record. That was up 14% from 2,999 individuals in 2013, the previous record.